Here's another question: why is she on a boat with John at the end of the episode? Wouldn't she be riding the dragon back? Is she just "so into him"? After what happened to Theon, isn't it kind of dangerous for her to be on a boat?
I mean, questioning the believability of travel distances in a show about dragons and zombies and white walkers seems a little silly - but part of what has made it a fun show is that, under the circumstances, it seems pretty believable.
I agree the whole Joss Wheadon "Superfriends walk to the north" was pretty rushed.